ci: fix the anaconda, wheel, external-zstd and flaky test workflows

.github/workflows/external-zstd.yml

@@ -61,4 +61,11 @@ jobs:
 
       - name: Build
         run: |
+          # Homebrew's prefix (/opt/homebrew on Apple Silicon) isn't on the
+          # default compiler search paths, and its libzstd is arm64 only, so
+          # don't build the universal2 binary the Python framework asks for.
+          ZSTD_PREFIX="$(brew --prefix zstd)"
+          export CFLAGS="-I${ZSTD_PREFIX}/include"
+          export LDFLAGS="-L${ZSTD_PREFIX}/lib"
+          export ARCHFLAGS="-arch arm64"
           python -m pip install --config-settings=--global-option=--system-zstd .

ci/conda/meta.yaml

@@ -1,8 +1,12 @@
-{% set data = load_setup_py_data() %}
+# Don't use load_setup_py_data(): it runs setup.py inside the conda-build
+# process, and setup.py's sys.path.insert(0, ".") then makes the unbuilt
+# zstandard package in the source tree shadow the zstandard bindings that
+# conda-package-handling needs for .conda support.
+{% set version_match = load_file_regex(load_file="../../c-ext/python-zstandard.h", regex_pattern='PYTHON_ZSTANDARD_VERSION "([^"]+)"', from_recipe_dir=True) %}
 
 package:
   name: zstandard
-  version: "{{ data.get('version') }}"
+  version: "{{ version_match.group(1) }}"
 
 source:
   path: ../../

pyproject.toml

@@ -42,14 +42,20 @@ requires = [
 build-backend = "setuptools.build_meta"
 
 [dependency-groups]
-dev = [
+# Dependencies needed to run the test suite. cibuildwheel installs this group
+# unlocked inside its build containers, so keep it free of packages (like mypy)
+# without wheels for every platform we build.
+test = [
     "cffi~=1.17; platform_python_implementation != 'PyPy' and python_version < '3.14'",
     "cffi>=2.0.0b; platform_python_implementation != 'PyPy' and python_version >= '3.14'",
     "hypothesis==6.111.0",
-    "mypy>=1.17.1",
     "pytest>=8.4.1",
     "pytest-xdist>=3.8.0",
 ]
+dev = [
+    { include-group = "test" },
+    "mypy>=1.17.1",
+]
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
@@ -71,7 +77,7 @@ test-command = [
     "pytest -v --numprocesses=auto",
     "PYTHON_ZSTANDARD_IMPORT_POLICY=cffi pytest -v --numprocesses=auto",
 ]
-test-groups = ["dev"]
+test-groups = ["test"]
 test-sources = ["tests"]
 
 [tool.cibuildwheel.linux]

tests/conftest.py

@@ -25,7 +25,9 @@ def pytest_configure(config):
     default_settings = hypothesis.settings(deadline=10000)
     hypothesis.settings.register_profile("default", default_settings)
 
-    ci_settings = hypothesis.settings(deadline=20000, max_examples=1000)
+    # Shared CI runners (notably the Intel macOS ones) are slow and noisy
+    # enough that per-example deadlines only produce flaky failures.
+    ci_settings = hypothesis.settings(deadline=None, max_examples=1000)
     hypothesis.settings.register_profile("ci", ci_settings)
 
     expensive_settings = hypothesis.settings(deadline=None, max_examples=10000)